Multilayer printed wiring board

ABSTRACT

A multilayer printed wiring board  10  includes: a mounting portion  60  on the top surface of which is mounted a semiconductor element that is electrically connected to a wiring pattern  32 , etc.; and a capacitor portion  40  having a high dielectric constant layer  43 , formed of ceramic and first and second layer electrodes  41  and  42  that sandwich the high dielectric constant layer  43 . One of either of the first and second layer electrodes  41  and  42  is connected to a power supply line of the semiconductor element and the other of either of the first and second layer electrodes  41  and  42  is connected to a ground line. In this multilayer printed wiring board  10 , high dielectric constant layer  43  included in the layered capacitor portion  40 , which is connected between the power supply line and the ground line, is formed of ceramic. With this structure, the static capacitance of the layered capacitor portion  40  can be high, and an adequate decoupling effect is exhibited even under circumstances in which instantaneous potential drops occur readily.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims the benefit of priorityunder 35 U.S.C. §120 from U.S. Ser. No. 11/356,350, filed Feb. 17, 2006,which is a continuation application of International Application No.PCT/JP2004/018526, filed on Dec. 6, 2004, and claims the benefit ofpriority under 35 U.S.C. §119 from Japanese Patent Application Nos.2003-407501, filed Dec. 5, 2003 and 2004-350731, filed Dec. 3, 2004, thecontents of which are incorporated by reference herein in theirentirety.

BACKGROUND ART

1. Field of the Invention

This invention concerns a multilayer printed wiring board havingbuild-up portions, in which wiring patterns, laminated in plural layersvia insulating layers, are electrically connected to each other by meansof via holes in the insulating layers.

2. Description of the Prior Art

Various structures have been proposed for multilayer printed wiringboards having build-up portions. In the build-up portions of theproposed multilayer printed boards, wiring patterns, laminated in plurallayers via insulating layers, are electrically connected to each otherby means of via holes in the insulating layers. In this type ofmultilayer printed wiring board, the potential of the power supply linemay drop instantaneously due to switching noise when a mountedsemiconductor element is switched on and off at a high speed. In orderto restrain such instantaneous potential drops, decoupling by connectionof a capacitor portion between the power supply line and the ground linehas been proposed. As a capacitor portion for this purpose, JP-A2001-68858 proposes the provision of a layered capacitor portion insidea multilayer printed wiring board.

SUMMARY OF THE INVENTION

The present invention provides a multilayer printed wiring board havingbuild-up portions in which multiple wiring patterns are laminated inlayers via insulating layers and are electrically connected to eachother by means of via holes formed in the insulating layers. Themultilayer printed wiring board includes: a mounting portion, on thesurface of which is mounted a semiconductor element that is electricallyconnected to the above-described wiring patterns; and a layeredcapacitor portion that is disposed between the mounting portion and thebuild-up portion and includes a high dielectric constant layer formed ofceramic and first and second layer electrodes sandwiching the highdielectric constant layer, where one of either of the first and secondlayer electrodes is connected to a power supply line of theabove-described semiconductor element and the other of either of theabove-described first and second layer electrodes is connected to aground line.

In this multilayer printed wiring board, the high dielectric constantlayer of the layered capacitor portion, which is connected between thepower supply line and the ground line, is formed of ceramic. In thisstructure, the dielectric constant and the static capacitance can behigh, compared with those in the conventional arrangement that uses anorganic resin blended with inorganic filler. Therefore, an adequatedecoupling effect is exhibited even when the on/off frequency of thesemiconductor element is high and in the range of several GHz to severaldozen GHz (for example, 3 GHz to 20 GHz).

In the multilayer printed wiring board of the invention, the highdielectric constant layer that is preferably prepared by calcining ahigh dielectric constant material apart from the build-up portion, andis joined to the build-up portion. A build-up portion is generallyprepared under a temperature condition of not more than 200° C., and itis difficult to calcine and make a high dielectric constant materialinto a ceramic. Therefore the high dielectric constant material ispreferably calcined and made into a ceramic apart from the build-upportion. The high dielectric constant layer is not restricted inparticular, but is preferably prepared by calcining, for example, a rawmaterial containing one type or two or more types of metal oxideselected from the group consisting of: barium titanate (BaTiO₃),strontium titanate (SrTiO₃), tantalum oxide (TaO₃, Ta₂O₅), leadzirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), leadniobium zirconate titanate (PNZT), lead calcium zirconate titanate(PCZT), and lead strontium zirconate titanate (PSZT).

In the multilayer printed wiring board of the invention, the first layerelectrode may have a solid pattern having passage holes, through whichrod terminals connected to the second layer electrode pass in anon-contacting manner, at the lower surface side of the high dielectricconstant layer, and the second layer electrode may have a solid patternhaving passage holes, through which rod terminals connected to the firstlayer electrode, pass in a non-contacting manner, at the upper surfaceside of the high dielectric constant layer. With this arrangement, sincethe areas of the first and second layer electrodes of the layeredcapacitor portion can be large, the static capacitance of the layeredcapacitor portion can be high. Also, since the layered capacitor portioncan be charged with charges via a short wiring length from an externalpower supply source and power can be supplied to the semiconductorelement via a short wiring length from the layered capacitor portion, anadequate decoupling effect can be provided and inadequacy of powersupply will be unlikely to occur even with a semiconductor element witha short on/off interval of several GHz to several dozen GHz (forexample, 3 GHz to 20 GHz). Each of the solid patterns may be provided ata portion or across the entirety of the upper surface or the lowersurface of the high dielectric constant layer.

In the printed wiring board of the invention, the mounting portion mayhave a plurality of pads connected to the electrodes of thesemiconductor element, and the number of rod terminals that areelectrically connected to pads of the same potential as the first layerelectrode and passing through the second layer electrode in anon-contacting manner may be less than the number of pads of the samepotential as the first layer electrode. The number of passage holes,through which the rod terminals that are connected to the pads of thesame potential as the first layer electrode and pass through the secondlayer electrode in a non-contacting manner, is lessened. Thus, the areaof the second layer electrode can be large and the static capacitance ofthe layered capacitor portion can be high.

In the printed wiring board of the invention, the mounting portion mayhave a plurality of pads connected to the electrodes of thesemiconductor element, and the number of rod terminals, which areelectrically connected to pads of the same potential as the second layerelectrode and passing through the first layer electrode in anon-contacting manner, may be less than the number of pads of the samepotential as the second layer electrode. The number of passage holes,through which the rod terminals that are connected to the pads of thesame potential as the second layer electrode and pass the first layerelectrode in a non-contacting manner, is lessened. Thus, the area of thefirst layer electrode can be large and the static capacitance of thelayered capacitor portion can be high. Here, the rod terminals connectedto pads of the same potential as the second layer electrode may pass notjust through the first layer electrode but also through the second layerelectrode in a non-contacting manner.

A portion of the above-described two types of rod terminals (that is,the rod terminals that are connected to the pads of the same potentialas the first layer electrode and passing through the second layerelectrode in a non-contacting manner, and the rod terminals that areconnected to the pads of the same potential as the second layerelectrode and passing through the first layer electrode in anon-contacting manner) may be aligned at least partially alternatinglyin a lattice-like or zigzag manner. With this arrangement, the loopinductance is made low and instantaneous drops of the power supplypotential can be prevented more readily.

In one modified structure of the multilayer printed wiring board of theinvention, the mounting portion may have first pads that are connectedto one of either of a power supply electrode and a ground electrode ofthe semiconductor element, and second pads that are connected to theother electrode. In this structure, some of the first pads have a firstrod terminal which passes through the second layer electrode in anon-contacting manner, and are electrically connected via the first rodterminal to the first layer electrode and one of the electrodes of anexternal power supply, while the others of the first pads do not havethe first rod terminal in themselves and are electrically connected tothe first pads having the first rod terminal. Some of the second padshave a second rod terminal which passes through the first layerelectrode in a non-contacting manner, and are electrically connected viathe second rod terminal to the second layer electrode and the otherelectrode of the external power supply, while the others of the secondpads do not have the second rod terminal in themselves and areelectrically connected to the second pads having the second rodterminal. With this arrangement, the number of the first rod terminalsand the second rod terminals can be restricted and the number of passageholes, through which these rod terminals pass the first layer electrodeand the second layer electrode, is lessened. Thus, the areas of thefirst and second layer electrodes can be large and the staticcapacitance of the layered capacitor portion can be high. It ispossible, for example, to arrange the first and second layer electrodesas substantially solid patterns. Also, with this arrangement, thelayered capacitor portion can be charged with charges via a short wiringlength from an external power supply source and power can be supplied tothe semiconductor element via a short wiring length from the layeredcapacitor portion. Thus, an adequate decoupling effect can be providedand inadequacy of power supply will be unlikely to occur even with asemiconductor element with a short on/off interval of several GHz toseveral dozen GHz (for example, 3 GHz to 20 GHz).

In another modified structure of the multilayer printed wiring board ofthe invention, the mounting portion may have first pads that areconnected to one of either of a power supply electrode and a groundelectrode of the semiconductor element, and second pads that areconnected to the other electrode. In this structure, some of the firstpads have a first rod terminal which passes through the second layerelectrode in a non-contacting manner, and are electrically connected viathe first rod terminal to the first layer electrode and one of theelectrodes of an external power supply, while the others of the firstpads do not have the first rod terminal in themselves and areelectrically connected to the first pads having the first rod terminal.Some of the second pads have a second rod terminal, which passes throughboth the first layer electrode and the second layer electrode in anon-contacting manner, and are connected via the second rod terminal tothe other electrode of the external power supply and the others of thesecond pads do not have the second rod terminal in themselves and areelectrically connected to at least one of either of the second layerelectrode and the second pads having the second rod terminal. With thisarrangement, the number of the first rod terminals and the second rodterminals can be restricted and the number of passage holes, throughwhich these rod terminals pass the first layer electrode and the secondlayer electrode, is lessened. Thus, the areas of the first and secondlayer electrodes can be large and the static capacitance of the layeredcapacitor portion can be high. It is possible for example, to arrangethe first and second layer electrodes as substantially solid patterns.Also, with this arrangement, the layered capacitor portion can becharged with charges via a short wiring length from an external powersupply source and power can be supplied to the semiconductor element viaa short wiring length from the layered capacitor portion. Thus, anadequate decoupling effect can be provided and inadequacy of powersupply will be unlikely to occur even with a semiconductor element witha short on/off interval of several GHz to several dozen GHz (forexample, 3 GHz to 20 GHz).

In the multilayer printed wiring board with the above structures wherethe first rod terminals and the second rod terminals are provided, atleast a portion of the first rod terminals and the second rod terminalsmay be aligned alternatingly in a lattice-like or zigzag manner. Withthis arrangement, the loop inductance is made low, and instantaneousdrops of the power supply potential can be prevented more readily.

In the multilayer printed wiring board of the invention, the distancebetween the first and second layer electrodes may be set to not morethan 10 μm so that a short will practically not occur in the layeredcapacitor portion. With this arrangement, the distance betweenelectrodes of the layered capacitor portion is adequately small, and thestatic capacitance of this layered capacitor portion can be high.

In the multilayer printed wiring board of the invention, the capacitorportion is preferably formed below the semiconductor element mounted onthe mounting portion. With this arrangement, power can be supplied tothe semiconductor element via the minimum wiring length.

The multilayer printed wiring board may have a chip capacitor installedat the top surface side at which the mounting portion is disposed and isconnected to the first and second layer electrodes. In the case wherethe static capacitance is inadequate with just the layered capacitorportion, the inadequacy can be supplemented by the chip capacitor.Though the decoupling effect degrades the longer the wiring between thechip capacitor and the semiconductor element, the wiring to thesemiconductor element can be short and the degradation of the decouplingeffect can be restrained in this arrangement because the chip capacitoris installed at the top surface side where the mounting portion isdisposed. Also, the power loss from the chip capacitor to thesemiconductor element is made small in this arrangement because the chipcapacitor and the semiconductor element are connected via the layeredcapacitor portion.

The multilayer printed wiring board of the invention may have a stressrelaxing portion formed of an elastic material and disposed between themounting portion and the layered capacitor portion. In this structure,even if stress occurs due to a thermal expansion difference between thesemiconductor element mounted on the mounting portion and the layeredcapacitor portion or the build-up portion, the stress relaxing portionabsorbs the stress. Thus, the reliability of connection, the reliabilityof insulation, etc., will thus not readily lowered. Also, though thehigh dielectric constant layer of the layered capacitor portion is thin,brittle, and thus tends to crack readily, the forming of cracks can beprevented by the presence of the stress relaxing portion. Here, thestress relaxing portion may be formed just below the semiconductorelement that is mounted on the above-described mounting portion. Sincestress due to a thermal expansion difference mainly becomes a problembelow the semiconductor element, the material cost can be held down byforming the stress relaxing portion below the semiconductor element. Thematerial of such a stress relaxing portion is not restricted inparticular, but may be a modified epoxy based resin sheet, apolyphenylene ether based resin sheet, a polyimide based resin sheet, acyanoester based resin sheet, an imide based resin sheet, and otherorganic base resin sheets. Such an organic based resin sheet may containa thermoplastic resin, such as a polyolefin based resin or a polyimidebased resin, a thermosetting resin, such as silicone resin, or a rubberbased resin, such as SBR, NBR, urethane, etc., and may contain afibrous, filler, or flattened inorganic based material of silica,alumina, zirconia, etc. The stress relaxing portion preferably has aYoung's modulus in a range of 10 to 1000 MPa. When stress occurs due toa thermal expansion coefficient difference between the semiconductorelement mounted on the mounting portion and the layered capacitorportion, the stress relaxing portion within this range can adequatelyrelax the stress.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a multilayer printed wiring board 10 of anExample 1;

FIG. 2 is a longitudinal section (showing only the left side of acentral line) of the multilayer printed wiring board 10;

FIG. 3 is a schematic perspective view of a layered capacitor portion40;

FIG. 4 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 10;

FIG. 5 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 10;

FIG. 6 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 10;

FIG. 7 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 10;

FIG. 8 is a longitudinal section of a multilayer printed wiring board110 of an Example 2;

FIG. 9 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 110;

FIG. 10 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 110;

FIG. 11 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 110;

FIG. 12 is an explanatory diagram of a high dielectric constant sheet520 with corner portions;

FIG. 13 is a longitudinal section of a multilayer printed wiring board210 of an Example 3;

FIG. 14 is a schematic perspective view of a layered capacitor portion240;

FIG. 15 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 210;

FIG. 16 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 210;

FIG. 17 is an explanatory diagram of a process for manufacturing themultilayer printed wiring board 210; and

FIG. 18 is an explanatory diagram of a manufacturing process of anothermultilayer printed wiring board 210.

BEST MODE FOR CARRYING OUT THE INVENTION Example 1

Embodiments of this invention shall now be described with reference tothe drawings. FIG. 1 is a plan view of a multilayer printed wiring board10, which is an example of this invention, FIG. 2 is a longitudinalsection (showing only the left side of the central line) of multilayerprinted wiring board 10, and FIG. 3 is a schematic perspective view of alayered capacitor portion 40. As shown in FIG. 2, the multilayer printedwiring board 10 of the present example includes a core substrate 20, abuild-up portion 30 on the core substrate 20, and a layered capacitorportion 40. In the core substrate 20, wiring patterns 22 that are formedon the top and back surfaces are electrically connected to each othervia through hole conductors 24. In the build-up portion 30, wiringpatterns 32 and 22, which are laminated in plural layers via resininsulating layers 36 on the upper surface of the core substrate 20, areelectrically connected to each other by means of via holes 34. Thelayered capacitor portion 40 includes a high dielectric constant layer43 and first and second layer electrodes 41 and 42 that sandwich thehigh dielectric constant layer 43. The multilayer printed wiring board10 further includes a stress relaxing portion 50 formed of an elasticmaterial, a mounting portion 60 on which a semiconductor element ismounted, and chip capacitor positioning regions 70 disposed at theperiphery of the mounting portion 60.

The core substrate 20 has wiring patterns 22 formed of copper at boththe top and back surfaces of a core substrate main body 21 formed of BT(bismaleimide-triazine) resin or a glass epoxy substrate, etc., andthrough hole conductors 24 formed of copper on inner peripheral surfacesof through holes that pass through from the top to back of the coresubstrate main body 21. The wiring patterns 22 at the respectivesurfaces are electrically connected via through hole conductors 24.

The build-up portions 30 are formed by layering resin insulating layers36 and wiring patterns 32 alternatingly on the top and back surfaces ofthe core substrate 20, and the respective wiring patterns 32 areelectrically connected through via holes 34 that pass through from thetop to back of insulating resin layers 36. Such build-up portions 30 areformed by any of known subtractive methods and additive methods(including semi-additive methods and full additive methods) and are, forexample, formed as follows. First, resin sheets, which are to becomeresin insulating layers 36, are adhered respectively onto the top andback surfaces of the core substrate 20. Here, the Young's modulus atroom temperature of each resin insulating layer 36 is 2 to 7 GPa. Eachresin sheet is formed of a modified epoxy based sheet, a polyphenyleneether based resin sheet, a polyimide based resin sheet, or a cyanoesterbased resin sheet, etc., and the thickness thereof is approximately 20to 80 μm. This resin sheet may have silica, alumina, zirconia, or otherinorganic component dispersed therein. Each adhered resin sheet is thenmade into a resin insulating layer 36 by forming through holes thereinby means of a carbon dioxide gas laser, UV laser, YAG laser, excimerlaser, etc., and the surface of the resin insulating layer 36 and theinterior of the through holes are subject to electroless copper platingand made into a conductive layer. A plating resist is then formed on theconductive layer and after subjecting the portions at which the platingresist is not formed to electrolytic copper plating, the electrolesscopper plating below the resist is removed by an etching solution toform wiring pattern 32. The conductive layers at the interiors of thethrough holes become via holes 34. This procedure is then repeated toform build-up portions 30.

The layered capacitor portion 40 includes high dielectric constant layer43 formed by calcining a ceramic-based high dielectric constant materialat a high temperature, and first layer electrode 41 and second layerelectrode 42 that sandwich the high dielectric constant layer 43. Ofthese layered capacitor portion 40, the first layer electrode 41 is acopper electrode that is electrically connected to ground pads 61 of themounting portion 60, and the second layer electrode 42 is a copperelectrode that is electrically connected to the power supply pads 62 ofthe mounting portion 60. The first and second layer electrodes 41 and 42are thus respectively connected to a ground line and a power supply lineof the semiconductor element mounted on the mounting portion. The firstlayer electrode 41 is a solid pattern formed on the lower surface ofhigh dielectric constant layer 43 and has passage holes 41 a, throughwhich via holes 62 b connected to power supply pads 62 pass in anon-contacting manner. Though the respective power supply pads 62 areconnected to the second layer electrode 42 through via holes 62 a, viaholes 62 b are disposed in correspondence to a portion of via holes 62a. This is because the respective via holes 62 a are connected to thesecond layer electrode 42 and thus as long as there is at least one viahole 62 b that extends downwards from the second layer electrode 42,connection to the power supply line can be achieved through that viahole 62 b. The second layer electrode 42 is a solid pattern formed onthe upper surface of high dielectric constant layer 43 and has passageholes 42 a, through which via holes 61 a connected to ground pads 61pass in a non-contacting manner. The distance between the first andsecond layer electrodes 41 and 42 is set to a distance that is not morethan 10 μm and yet with which shorting practically does not occur. Thehigh dielectric constant layer 43 is formed by making a high dielectricconstant material, containing one or two or more types of metal oxideselected from the group consisting of BaTiO₃, SrTiO₃, TaO₃, Ta₂O₅, PZT,PLZT, PNZT, PCZT, and PSZT, into a thin film of 0.1 to 10 μm andthereafter calcining and making the high dielectric constant materialinto a ceramic. The details of a process for manufacturing the layeredcapacitor portion 40 shall be described later.

Though partially overlapping with the description above, the layeredcapacitor portion 40 shall now be described in more detail. In thelayered capacitor portion 40, the first layer electrode 41 iselectrically connected through via holes 61 a to ground pads 61 of themounting portion 60 and the second layer electrode 42 is electricallyconnected through via holes 62 a to power supply pads 62 of the mountingportion 60. The first and second layer electrodes 41 and 42 are thusconnected to the ground line and the power supply line, respectively ofthe semiconductor element mounted on the mounting portion 60. The firstlayer electrode 41 is a solid pattern formed on the lower surface of thehigh dielectric constant layer 43 and has passage holes 41 a, throughwhich via holes 62 b connected to the second layer electrode 42 pass ina non-contacting manner. Though via holes 62 b may be provided incorrespondence to all power supply pads 62, here, via holes 62 b areprovided in correspondence to a portion of power supply pads 62. This isbecause the second layer electrode 42 is connected through therespective via holes 62 a to the respective power supply pads 62 andthus as long as there is at least one via hole 62 b that extendsdownwards from the second layer electrode 42, all power supply pads 62can be connected to an external power supply line through that via hole62 b. By thus providing via holes 62 b in correspondence to a portion ofpower supply pads 62, the number of passage holes 41 a to be provided inthe first layer electrode 41 can be small and since the area of thefirst layer electrode 41 can be large, so that the static capacitance oflayered capacitor portion 40 can be high. The positions at which passageholes 41 a are to be formed are determined depending on the staticcapacitance of layered capacitor portion 40, the positioning of viaholes 62 a, etc. The second layer electrode 42 is a solid pattern formedon the upper surface of high dielectric constant layer 43 and haspassage holes 42 a, through which via holes 61 a connected to groundpads 61 pass in a non-contacting manner. Though passage holes 42 a maybe provided in correspondence to all ground pads 61, here, a pluralityof ground pads 61 are connected together at the upper side of the secondlayer electrode 42 and via holes 61 a are formed for just a portion ofthese ground pads 61 and are made to pass through passage holes 42 a ofthe second layer electrode 42 in a non-contacting manner. By thusproviding via holes 61 a in correspondence to a portion of ground pads61, the number of passage holes 42 a to be provided in the second layerelectrode 42 can be small and since the area of the second layerelectrode 42 can be large, so that the static capacitance of layeredcapacitor portion 40 can be high. The positions at which passage holes42 a are to be formed are determined depending on the static capacitanceof the layered capacitor portion 40, the positioning of via holes 62 a,etc.

The stress relaxing portion 50 is formed of an elastic material. Theelastic material is not restricted in particular, but may be a modifiedepoxy based resin sheet, a polyphenylene ether based resin sheet, apolyimide based resin sheet, a cyanoester based resin sheet, an imidebased resin sheet, and other organic base resin sheets can be cited asexamples. Such an organic based resin sheet may contain a thermoplasticresin, such as a polyolefin based resin or a polyimide based resin, athermosetting resin, such as silicone resin, or a rubber based resin,such as SBR, NBR, urethane, etc., and may contain a fibrous, filler, orflattened inorganic based material of silica, alumina, zirconia, etc.The stress relaxing portion 50 preferably has a low Young's modulus of10 to 1000 MPa. When stress occurs due to a thermal expansioncoefficient difference between the semiconductor element mounted to themounting portion 50, and the layered capacitor portion, the Young'smodulus of the stress relaxing portion 50 within this range canadequately relax the stress.

The mounting portion 60 is the region on which the semiconductor elementis mounted and is formed on the top surface of the multilayer printedwiring board 10. On this mounting portion 60, ground pads 61, powersupply pads 62, and signal pads 63 are aligned in a lattice-like orzigzag manner (see FIG. 1). Ground pads 61 and power supply pads 62 maybe aligned in a lattice-like or zigzag manner near the center and signalpads 63 may be aligned in a lattice-like manner, a zigzag manner, orrandomly in the periphery. Ground pads 61 and power supply pads 62 arepreferably aligned alternatingly. The number of terminals of themounting portion 60 is 1000 to 300000. A plurality of the chip capacitorpositioning regions 70 (see FIG. 1) are formed in the periphery of themounting portion 60. A plurality of pairs of the ground pad 71 and powersupply pad 72 are formed in the chip capacitor positioning regions 70 soas to be connected with the ground terminals and power supply terminals,respectively, of the chip capacitors 73. The respective ground pads 71are connected via first layer electrode 41 of the layered capacitorportion 40 to the negative electrode of an external power supply and therespective power supply pads 72 are connected via the second layerelectrode 42 to the positive electrode of the external power supply.

An example of use of the multilayer printed wiring board 10 describedabove shall now be described. First, the power supply terminal and theground terminal of a chip capacitor 73 are joined by soldering to theground pad 71 and power supply pad 72, respectively, of a chip capacitorpositioning region 70. A semiconductor element having a plurality ofsolder bumps aligned on the back surface is then set on the mountingportion 60. In this process, the ground terminals, the power supplyterminals, and the signal terminals of the semiconductor element are putin contact with ground pads 61, power supply pads 62, and signal pads63, respectively of the mounting portion 60. The respective terminalsare then joined by soldering by the reflow method. Then, the multilayerprinted wiring board 10 is joined by soldering to another printed wiringboard of the mother board. In this process, solder bumps are formed inadvance on the pads formed on the back surface of the multilayer printedwiring board 10 and then joined by reflow in a state of contactingcorresponding pads of another printed wiring board.

Procedures for manufacturing multilayer printed wiring board 10 of thepresent example shall now be described. Since the procedures forpreparing the core substrate 20 and the build-up portion 30 are wellknown, the description here shall mainly concern the procedures forpreparing the layered capacitor portion 40 and the stress relaxingportion 50. FIGS. 4 to 7 are explanatory diagrams of these procedures.

First, as shown in FIG. 4A, the core substrate 20 having the build-upportion 30 formed at least on one surface was prepared. An interlayerinsulating layer 410 was adhered onto the build-up portion 30 using avacuum laminator, under lamination conditions of a temperature of 50 to150° C. and a pressure of 0.5 to 1.5 MPa. A high dielectric constantsheet 420, which had been prepared in advance, was then adhered onto theinterlayer insulating layer 410 under lamination conditions of atemperature of 50 to 150° C. and a pressure of 0.5 to 1.5 MPa using avacuum laminator and then cured for three hours at 150° C. (see FIG.4B). Here, high dielectric constant sheet 420 is prepared as follows.That is, a high dielectric constant material, containing one or two ormore types of metal oxide selected from the group consisting of BaTiO₃,SrTiO₃, TaO₃, Ta₂O₅, PZT, PLZT, PNZT, PCZT, and PSZT, is printed in theform of a thin film of 0.1 to 10 μm thickness onto a copper foil 422 (tosubsequently become the first layer electrode 41) of 12 μm thicknessusing a roll coater, doctor blade, or other printing device and therebymade into an uncalcined layer. After printing, this uncalcined layer iscalcined in vacuum or under a non-oxidizing atmosphere of N₂ gas, etc.at a temperature range of 600 to 950° C. and made into a high dielectricconstant layer 424. Thereafter, a metal layer of copper, platinum, orgold, etc., is formed on the high dielectric constant layer 424 using asputterer or other vacuum vapor deposition device and by addingapproximately 10 μm of copper, nickel, tin, or other metal byelectrolytic plating, etc., onto this metal layer, an upper metal layer426 (subsequently forming a portion of the second layer electrode 42) isformed. High dielectric constant sheet 420 can be thus obtained.

A commercially available dry film 430 was then adhered onto thesubstrate with the high dielectric constant sheet 420 laminated thereon(see FIG. 4C), and pattern forming of the high dielectric constant sheet420 was then performed by carrying out exposure and development (seeFIG. 4D), etching (see FIG. 4E), and film removal (see FIG. 4F), whichare normally carried out in the pattern forming of a multilayer printedwiring board. In the etching process, a cupric chloride etching solutionwas used.

A dry film 440 was then adhered again onto the substrate in the middleof preparation on which pattern forming of the high dielectric constantsheet 420 had been performed (see FIG. 5A), and pattern forming of themetal layer 426 and high dielectric constant layer 424 on the highdielectric constant sheet 420 was then performed by carrying outexposure and development (see FIG. 5B), etching (see FIG. 5C), and filmremoval (see FIG. 5D). Though a cupric chloride etching solution wasused in the etching process, the process was carried out in a short timeso that after the etching metal layer 426 and the high dielectric layer424, the copper foil 422 was etched only slightly.

The substrate in the middle of preparation, with which pattern formingof the metal layer 426 and high dielectric constant layer 424 had beenperformed, was then filled with an interlayer filling resin 450 using asqueegee (see FIG. 5E) and dried for 20 minutes at 100° C. Here, theinterlayer filling resin 450 was prepared by placing 100 weight parts ofbisphenol F epoxy monomer (trade name: YL983U; made by Yuka Shell EpoxyCo., Ltd.; molecular weight: 310), 72 weight parts of spherical SiO₂particles of an average particle diameter of 1.6 μm, a maximum particlediameter of not more than 15 μm, and having a silane coupling agentcoated on the surface (trade name: CRS1101-CE; made by Adtec Co., Ltd.),and 1.5 weight parts of a leveling agent (trade name: Pellenol S4; madeby SAN NOPCO Ltd.) in a container and mixing these by stirring. Here,the viscosity at 23±1° C. was 30 to 60 Pa/s. As a curing agent, 6.5weight parts of an imidazole curing agent (made by Shikoku Corp.; tradename: 2E4MZ-CN) was used. After filling with and then drying resin 450,the top surface of the substrate in the middle of preparation waspolished and flattened until the surface of the upper metal layer 426became exposed, and the resin 450 was then cured by heating at 100° C.for 1 hour and at 150° C. for 1 hour and thereby made into aninter-high-dielectric-constant-layer filling layer 452 (see FIG. 5F).

Through holes 454 that reach the top surface of the wiring pattern 32 ofthe build-up portion 30 were then formed by means of a carbon dioxidegas laser, UV laser, YAG laser, or excimer laser, etc., at predeterminedpositions of the top surface of the substrate in the middle ofpreparation on which the inter-high-dielectric-constant-layer fillinglayer 452 had been formed (see FIG. 6A). After then adding anelectroless plating catalyst on the top surface of the substrate in themiddle of preparation, the substrate was immersed in an aqueouselectroless copper plating solution to form an electroless copperplating film 456 of 0.6 to 3.0 μm thickness on the inner walls of thethrough holes 454, the surface of high dielectric constant sheet 420,and the surface of the inter-high-dielectric-constant-layer fillinglayer 452 (see FIG. 6B). The composition of the aqueous electrolessplating solution used was: 0.03 mol/L of copper sulfate, 0.200 mol/L ofEDTA, 0.1 g/L of HCHO, 0.1 mol/L of NaOH, 100 mg/L of α,α′-bipyridyl,and 0.1 g/L of polyethylene glycol (PEG).

A commercially available dry film 460 was then adhered onto electrolesscopper plating film 456 (see FIG. 6C), through holes 462 were formed byexposure/development and etching (see FIG. 6D), and an electrolyticcopper plating film 464 of 25 μm was formed on the surface of thethrough holes 462 (see FIG. 6E). The composition of the electrolyticcopper plating solution used was: 200 g/L of sulfuric acid, 80 g/L ofcopper sulfate, and 19.5 ml/L of an additive (Cupracid GL, made byATOTECH Japan Co., Ltd.). The electrolytic copper plating was carriedout under the conditions of a current density of 1 A/dm², a duration of115 minutes, and a temperature of 23±2° C. Dry film 460 was then peeledoff, and the portions on which dry film 460 had remained, that is, theportions of electroless copper plating film 456 existing betweenportions of electrolytic copper plating film 464, and the exposedportions of the upper metal layer 426 of the high dielectric constantsheet 420 were etched by a sulfuric acid—hydrogen peroxide based etchingsolution (see FIG. 6F). Through these steps, the layered capacitorportion 40 was formed on the build-up portion 30. That is, copper foil422 corresponds to being the first layer electrode 41, the highdielectric constant layer 424 corresponds to being the high dielectricconstant layer 43, and the upper metal layer 426, the electroless copperplating film 456 and the electrolytic copper plating film 464 correspondto being the second layer electrode 42.

The substrate in the middle of preparation, on which the electrolyticcopper plating film 464 had been formed, was then subject to ablackening treatment in a blackening bath (oxidizing bath) of an aqueoussolution containing NaOH (10 g/L), NaClO₂ (40 g/L), and Na₃PO₄ (6 g/L)and a reduction treatment in a reducing bath of an aqueous solutioncontaining NaOH (10 g/L) and NaBH₄ (6 g/L) to roughen the surface of theelectrolytic copper plating film 464 (not shown). Thereafter, a resininsulating sheet 470 was adhered onto the layered capacitor portion 40by a vacuum laminator under lamination conditions of a temperature of 50to 150° C. and a pressure of 0.5 to 1.5 MPa, and curing at 150° C. wascarried out for 3 hours (see FIG. 7A). This resin insulating sheet 470is a modified epoxy based resin sheet, a polyphenylene ether based resinsheet, a polyimide based resin sheet, a cyanoester based resin sheet, oran imide based resin sheet, and may contain a thermoplastic resin, suchas a polyolefin based resin or a polyimide based resin, a thermosettingresin, such as silicone resin, or a rubber based resin, such as SBR,NBR, urethane, etc., and may have dispersed therein a fibrous, filler,or flattened inorganic based material of silica, alumina, zirconia, etc.The Young's modulus of this resin insulating sheet 470 is preferably 10to 1000 MPa. The Young's modulus of the resin insulating sheet 470within this range can adequately relax the stress that occurs due to athermal expansion coefficient difference between the semiconductorelement and the substrate.

Through holes 472 of 65 μmφ were then formed in the resin insulatingsheet 470 using a CO₂ laser under the conditions of an energy density of2.0 mj and 1 shot (see FIG. 7B). Immersion for 10 minutes in a solutionof 80° C. containing 60 g/L of permanganic acid was then performed toroughen the surface of the resin insulating sheet 470. The substrate inthe middle of preparation that had been roughened was then immersed in aneutralizing solution (trade name: Circuposit MLB Neutralizer; made byShipley Company L.L.C) and was washed with water. The substrate wasfurthermore immersed in a catalyst solution containing palladiumchloride (PdCl₂) and stannous chloride (SnCl₂) to precipitate palladiummetal and thereby add a palladium catalyst to the surface (including theinner walls of the through holes 472) of the resin insulating sheet 470.The substrate was then immersed in an aqueous electroless copper platingsolution and was treated for 40 minutes at a liquid temperature of 34°C. to form an electroless copper plating film of 0.6 to 3.0 μm thicknesson the surface of resin insulating sheet 470 and the wall surfaces ofthe through holes 472 (not shown). The composition of the aqueouselectroless plating solution used was: 0.03 mol/L of copper sulfate,0.200 mol/L of EDTA, 0.1 g/L of HCHO, 0.1 mol/L of NaOH, 100 mg/L ofα,α′-bipyridyl, and 0.1 g/L of polyethylene glycol (PEG). The dry filmwas then formed on the electroless copper plating film and anelectrolytic copper plating film of 25 μm thickness was formed under thefollowing conditions (not shown). The composition of the electrolyticcopper plating solution used was: 200 g/L of sulfuric acid, 80 g/L ofcopper sulfate, and 19.5 ml/L of an additive (Cupracid GL, made byATOTECH Japan Co., Ltd.). The electrolytic copper plating was carriedout under the conditions of a current density of 1 A/dm², a duration of115 minutes, and a temperature of 23±2° C. The dry film 460 was thenpeeled off and the multilayer printed wiring board 10, such as shown inFIGS. 1 and 2, was obtained (FIG. 7C). The resin insulating sheet 470corresponds to being the stress relaxing portion 50. The copper platingfilms 474 that fill the through holes 472 correspond to being thevarious terminals 61, 62, and 63.

After the above, solder bumps may be formed by coating on and drying acommercially available solder resist composition, setting a soda limeglass substrate, on which a pattern of circles (mask pattern) of solderresist openings are drawn by a chromium layer, so that the side on whichthe chromium layer is formed is put in close contact with the solderresist layer, carrying out exposure and development with ultravioletrays and heating to form a solder resist layer pattern, with which theupper surfaces of the respective terminals 61, 62, and 63 are opened,performing electroless nickel plating and electroless gold plating toform a nickel plating layer and a gold plating layer, printing on solderpaste, and then carrying out reflow. The solder resist layer may eitherbe formed or not be formed.

With the multilayer printed wiring board 10 described in detail above,since the high dielectric constant layer 43 of the layered capacitorportion 40, which is connected between the power supply line and theground line, is made of ceramic, the dielectric constant can be high incomparison to the conventional case of using an organic resin having aninorganic filler blended in and the static capacitance of the layeredcapacitor portion 40 can be high. An adequate decoupling effect can thusbe provided and instantaneous potential drops are made unlikely to occureven if the on/off frequency of the semiconductor element is high and inthe range of several GHz to several dozen GHz (for example, 3 GHz to 20GHz).

The build-up portion 30 is normally prepared under a temperaturecondition of not more than 200° C. and it is thus difficult to calcine ahigh dielectric constant material and make it into a ceramic in themiddle of forming the build-up portion 30. However, in theabove-described example, since the high dielectric constant layer 43 oflayered capacitor portion 40 is prepared by calcining a high dielectricconstant material into a ceramic separately from the build-up portion30, the dielectric constant can be adequately high readily.

In the first layer electrode 41 consisting the layered capacitor portion40 is a solid pattern that is formed on the first surface, that is, thelower surface of the high dielectric constant layer 43 which is, of therespective surfaces of the high dielectric constant layer 43, is the farfrom the mounting portion 60. The second layer electrode 42 is a solidpattern that is formed on the second surface, that is, the upper surfaceof the high dielectric layer 43, which is close to the mounting portion60 and has passage holes 42 a, through which via holes 61 a connected tothe first layer electrode 41 pass in a non-contacting manner. The areasof the respective layered electrodes 41 and 42 can be thus adequatelylarge and the static capacitance of the layered capacitor portion 40 canbe high. Since the via holes 61 a connected to the first layer electrode41 and the via holes 62 a connected to the second layer electrode 42 arealigned alternatingly in lattice form, the loop inductance is low andinstantaneous potential drops can be prevented readily. The via holes 61a and the via holes 62 a may be aligned in an alternating zigzag manner,and the same effects can be obtained in this case as well.

Furthermore, in the layered capacitor portion 40, the distance betweenthe first and second layer electrodes 41 and 42 is set to a distancethat is not more than 10 μm and yet at which shorting will practicallynot occur. The distance between electrodes of the layered capacitorportion 40 is adequately small and the static capacitance of the layeredcapacitor portion 40 can be high.

In the case where the static capacitance is inadequate with just thelayered capacitor portion 40, chip capacitors 73 can be provided tocompensate the inadequact. That is, the chip capacitors 73 may bemounted as necessary. The decoupling effect is lowered as the wiringbetween the chip capacitor 73 and the semiconductor element is longer.However, in the above-described example, the chip capacitor 73 isinstalled on the top surface side at which the mounting portion 60 isdisposed. The wiring to the semiconductor element can be short and thelowering of the decoupling effect can be restrained.

Also, even if stress occurs due to a thermal expansion differencebetween the semiconductor element, mounted on the mounting portion 60and the layered capacitor 40 or the build-up portion 30, the stressrelaxing portion 50 adequately absorbs the stress. The stress relaxingportion 50 may be formed just below the semiconductor element mounted onthe mounting portion 60. Since stress due to a thermal expansiondifference mainly becomes a problem below the semiconductor element, thematerial cost can be held down by forming the stress relaxing portion 50at this portion.

This invention is by no means restricted to the above-described exampleand may obviously be put into practice in various modes within the scopeof the art of this invention.

Example 2

FIG. 8 is a longitudinal section (showing only the left side of acentral line) of a multilayer printed wiring board 110 of Example 2. Asshown in FIG. 8, the multilayer printed wiring board 110 of the presentexample has the same core substrate 20 as Example 1, the build-upportion 30 in which wiring patterns 32 and 22 laminated via resininsulating layer 36 on the upper surface of core substrate 20 areelectrically connected by via holes 34, an interlayer insulating layer120, laminated on the build-up portion 30, a layered capacitor portion140, laminated on the interlayer insulating layer 120 and arranged witha high dielectric constant layer 143 and the first and second layerelectrodes 141 and 142 that sandwich the high dielectric constant layer143, a stress relaxing portion 150, laminated on the high dielectricconstant layer 143 and formed of an elastic material, a mounting portion160, on which a semiconductor element is mounted, and the chip capacitorpositioning regions 170, provided at the periphery of mounting portion160.

In the layered capacitor portion 140 of the present example, the firstlayer electrode 141 is a copper electrode that is electrically connectedthrough via holes 161 a to ground pads 161 of the mounting portion 160,and the second layer electrode 142 is a copper electrode that iselectrically connected through via holes 162 a to power supply pads 162of the mounting portion 160. The first and second layer electrodes 141and 142 are thus connected to the ground line and the power supply line,respectively of the semiconductor element mounted on the mountingportion 160.

The first layer electrode 141 is a solid pattern formed on the lowersurface of the high dielectric constant layer 143 and has passage holes141 a, through which via holes 162 b connected to the second layerelectrode 142 pass in a non-contacting manner. Though via holes 162 bmay be provided in correspondence to all power supply pads 162, here,via holes 162 b are provided in correspondence to a portion of powersupply pads 162. The reason for this is as follows. That is, of allpower supply pads 162, some power supply pads 162 are connected throughvia holes 162 a to the second layer electrode 142 and the remainingpower supply pads 162 are electrically connected by unillustratedwirings (for example, wirings provided on the mounting portion 160) tothe other power supply pads 162 that are electrically connected throughvia holes 162 a to the second layer electrode 142, and since all powersupply pads 162 are thus connected to the second layer electrode 142, aslong as there is at least one via hole 162 b that extends downwards fromthe second layer electrode 142, all power supply pads 162 can beconnected to the external power supply line through that via hole 162 b.Since by providing via holes 162 b in correspondence to a portion ofpower supply pads 162, the number of passage holes 141 a to be providedin the first layer electrode 141 can be small, the area of the firstlayer electrode 141 can be large and the static capacitance of thelayered capacitor portion 140 can be high. The number of passage holes141 a and the positions at which passage holes 141 a are to be formedare determined depending on the static capacitance of the layeredcapacitor portion 140, the positioning of via holes 162 a, etc.

The second layer electrode 142 is a solid pattern formed on the uppersurface of the high dielectric constant layer 143 and has passage holes142 a, through which via holes 161 a connected to ground pads 161 passin a non-contacting manner. Though via holes 161 a may be provided incorrespondence to all ground pads 161, here, these are provided incorrespondence to a portion of ground pads 161. The reason for this isas follows. That is, since ground pads 161 are electrically connected toeach other by unillustrated wirings (for example, wirings provided onthe mounting portion 160), as long as there is at least one via hole 161a that extends downwards from a ground pad 161 and contacts the firstlayer electrode 141 without contacting the second layer electrode 142,all ground pads 161 can be connected to the external ground line throughthat via hole 161 a. Since by providing via holes 161 a incorrespondence to a portion of ground pads 161, the number of passageholes 142 a to be provided in the second layer electrode 142 can besmall, the area of the second layer electrode 142 can be large and thestatic capacitance of layered capacitor portion 140 can be high. Thenumber of passage holes 142 a and the positions at which passage holes142 a are to be formed are determined depending on the staticcapacitance of the layered capacitor portion 140, the positioning of viaholes 161 a, etc.

Since the static capacitance of the layered capacitor portion 140 canthus be made high, an adequate decoupling effect can be exhibited andthe transistor of the semiconductor element (IC) mounted on the mountingportion 160 will be unlikely to become short of power. The wiring forelectrically connecting ground pads 161, not having via holes below, toground pads 161 having via holes below, and the wiring for electricallyconnecting power supply pads 162, not having via holes below, to powersupply pads 162 having via holes below, may be provided on the mountingportion 60 or may be provided on the top surface of the core substrate20 or on the build-up portion 30. The connections may also be made by awiring layer disposed between the layered capacitor portion 140 and themounting portion 160.

The stress relaxing portion 150 is formed of the same elastic materialas in Example 1. Also, ground pads 161, power supply pads 162, andsignal pads 163, disposed on the mounting portion 160, are aligned in alattice-like or zigzag manner (see FIG. 1). Ground pads 161 and powersupply pads 162 may be aligned in a lattice-like or zigzag manner nearthe center and signal pads 163 may be aligned in a lattice-like manner,a zigzag manner, or randomly in the periphery. The number of terminalsof the mounting portion 60 is 1000 to 300000. A plurality of chipcapacitor positioning regions 170 are formed in the periphery of themounting portion 160. A plurality of pairs of ground pads 171 and powersupply pads 172 are formed in the chip capacitor positioning regions 170so as to be connected with the ground terminals and power supplyterminals, respectively, of chip capacitors 173,

The respective ground pads 171 are connected via the first layerelectrode 141 of the layered capacitor portion 140 to the negativeelectrode of an external power supply and the respective power supplypads 172 are connected via the second layer electrode 142 to thepositive electrode of the external power supply. In the present example,ground pads 161 and power supply pads 162 respectively correspond tobeing the first pads and the second pads of Claim 8, and via holes 161 aand via holes 162 b respectively correspond to being the first rodterminals and the second rod terminals of Claim 8.

The procedures for manufacturing the multilayer printed wiring board 110of the present example shall now be described with reference to FIGS. 9to 11.

First, as shown in FIG. 9A, a substrate 500 having the build-up portion30 formed at least on one surface of the core substrate 20 was preparedand using a vacuum laminator, an interlayer insulating layer 510 (tobecome interlayer resin layer 120 of FIG. 8; a thermosetting insulatingfilm; ABF-45SH, made by AJINOMOTO Co., Inc.) was adhered onto thebuild-up portion 30 under lamination conditions of a temperature of 50to 150° C. and a pressure of 0.5 to 1.5 MPa. A high dielectric constantsheet 520, which had been prepared in advance and having a structure inwhich a high dielectric constant layer 524 is sandwiched between acopper foil 522 and a copper foil 526, was then adhered onto theinterlayer insulating layer 510 under lamination conditions of atemperature of 50 to 150° C. and a pressure of 0.5 to 1.5 MPa using avacuum laminator and thereafter, drying at 150° C. was performed for 1hour (see FIG. 9B). At the stage of lamination, both copper foils 522and 526 of high dielectric constant sheet 520 are preferably solidlayers that do not have circuits formed therein. When portions of copperfoils 522 and 526 are removed by etching, etc., due to (i) portions, atwhich the percentages of metal remaining differ between the top and backsurfaces, and portions, at which the metal has been removed, becomingstarting points of bending or folding of the high dielectric constantsheet, (ii) the existence of corner portions (see FIG. 12) due toremoval of a copper foil portion and the concentrating of stress at suchportions, (iii) direct contacting of the laminator with the highdielectric constant layer, etc., cracks tend to form readily in the highdielectric constant layer and short circuiting may occur across therespective copper foils when such cracked portions are filled withplating in a subsequent plating step. Also when portions of theelectrodes are removed prior to lamination, the static capacitance ofthe high dielectric constant sheet decreases and in laminating the highdielectric constant sheet, the need to position and then adhere the highdielectric constant sheet and the build-up portion arises. Furthermore,since the high dielectric constant sheet is thin and does not haverigidity, the positional precision becomes poor when portions of thecopper foils are removed. In addition, since portions of the copperfoils must be removed in consideration of the alignment precision,somewhat large areas of the copper foils must be removed and thealignment precision will be poor since the high dielectric constantsheet is thin. Due to the above, at the stage of lamination, both copperfoils 522 and 526 of the high dielectric constant sheet 520 arepreferably solid layers in which circuits are not formed.

Procedures for preparing the high dielectric constant sheet 520 shallnow be described.

(1) Diethoxy barium and titanium bitetraisopropoxide, which had beenweighed out to provide concentrations of 1.0 moles/liter, were dissolvedin a mixed solvent of dehydrated methanol and 2-methoxyethanol (volumeratio: 3:2) in dried nitrogen and stirring was performed for 3 days atroom temperature under a nitrogen atmosphere to prepare an alkoxideprecursor composition solution. This precursor composition solution wasthen stirred while keeping at 0° C. and water that had been decarbonatedin advance was sprayed at a rate of 0.5 microliters/minute in a nitrogengas flow to carry out hydrolysis.

(2) The sol-gel solution thus prepared was passed through a 0.2 micronfilter to filter out precipitates, etc.

(3) The filtrate prepared in (2) above was spin coated at 1500 rpm for 1minute on the copper foil 522 (to subsequently become the first layerelectrode 141) of 12 μm thickness. The substrate onto which the solutionwas spin coated was then dried by keeping for 3 minutes on a hot platemaintained at 150° C. The substrate was then inserted in an electricoven kept at 850° C. and calcined for 15 minutes. Here, the viscosity ofthe sol-gel solution was adjusted so that the film thickness obtainedafter 1 time of spin coating, drying, and calcining will be 0.03 μm.Nickel, platinum, gold, or silver, etc., may be used instead of copperas the first layer electrode 141.

(4) Spin coating, drying, and calcining were repeated 40 times and ahigh dielectric constant layer 524 of 1.2 μm was obtained.

(5) Thereafter, using a sputterer or other vacuum vapor depositiondevice, a copper layer was formed on the high dielectric constant layer524, and by furthermore adding approximately 10 μm of copper byelectrolytic plating, etc., on the copper layer, the copper foil 526(subsequently forming a portion of the second layer electrode 142) wasformed. The high dielectric constant sheet 520 was thus obtained. Uponmeasuring the dielectric characteristics using an impedance/gain phaseanalyzer (trade name: 4194A; made by Hewlett-Packard DevelopmentCompany, L.P.) under the conditions of a frequency of 1 kHz, atemperature of 25° C., and an OSC level of 1V, the relative permittivitywas found to be 1,850. A metal layer of platinum, gold, etc., may beformed instead of the copper layer by the vacuum vapor deposition, and ametal layer of nickel, tin, etc., may be formed instead of the copperlayer by the electrolytic plating. Also, though the high dielectricconstant layer was formed of barium titanate, the high dielectricconstant layer may instead be formed of any of strontium titanate(SrTiO₃), tantalum oxide (TaO₃, Ta₂O₅), lead zirconate titanate (PZT),lead lanthanum zirconate titanate (PLZT), lead niobium zirconatetitanate (PNZT), lead calcium zirconate titanate (PCZT), and leadstrontium zirconate titanate (PSZT) by using another sol-gel solution.

As another method of preparing the high dielectric constant sheet 520,there is also the following method. That is, a barium titanate powder(HPBT Series, made by Fuji Titanium Industry Co., Ltd.) is dispersed ina binder solution, wherein, with respect to the total weight of thebarium titanate powder, 5 weight parts of polyvinyl alcohol, 50 weightparts of pure water, and 1 weight part of dioctyl phthalate or dibutylphthalate as a solvent-based plasticizer are mixed. The dispersion isthen printed as a thin film of approximately 5 to 7 μm thickness ontothe copper foil 522 (to subsequently become the first layer electrode141) of 12 μm thickness using a roll coater, doctor blade, α-coater, orother printing device and then dried for 1 hour at 60° C., 3 hours at80° C., 1 hour at 100° C., 1 hour at 120° C., and 3 hours at 150° C. andthereby made into an uncalcined layer. Besides BaTiO₃, a pastecontaining one or two or more types of metal oxide selected from thegroup consisting of SrTiO₃, TaO₃, Ta₂O₅, PZT, PLZT, PNZT, PCZT, and PSZTmay be printed as a thin film of 0.1 to 10 μm thickness using a rollcoater, doctor blade, or other printing device and then dried to anuncalcined layer. After printing, the uncalcined layer is calcined at atemperature range of 600 to 950° C. and thereby made into the highdielectric layer 524. Thereafter, using a sputterer or other vacuumvapor deposition device, a copper layer is formed on the high dielectricconstant layer 524 and by furthermore adding approximately 10 μm ofcopper by electrolytic plating, etc. on the copper layer, the copperfoil 526 (subsequently forming a portion of the second layer electrode142) is formed. A metal layer of platinum, gold, etc., may be formedinstead of the copper layer by the vacuum vapor deposition, and a metallayer of nickel, tin, etc., may be formed instead of the copper layer bythe electrolytic plating. Sputtering using barium titanate as the targetmay also be employed.

Through holes 530 and 531 were then formed by means of a carbon dioxidegas laser, UV laser, YAG laser, excimer laser, etc., at predeterminedpositions of the top surface of the substrate in the middle ofpreparation on which the high dielectric constant sheet 520 had beenformed (see FIG. 9C). Through holes 530 of deep depth are through holesthat pass through the high dielectric constant sheet 520 and interlayerinsulating layer 510 and reach the top surface of the wiring pattern 32of the build-up portion 30. Through holes 531 of shallow depth arethrough holes that pass through the copper foil 526 and high dielectricconstant layer 524 and reach the top surface of the copper foil 522.Here, in forming the through holes, first, the deep through holes 530were formed and then the shallow through holes 531 were formed. Thedepth was adjusted by changing the number of laser shots. Specifically,through holes 531 were formed using a UV laser made by Hitachi ViaMechanics, Ltd. at conditions of an output of 3 to 10 W, a frequency of30 to 60 kHz, and a number of shots of 4, and the through holes 530 wereformed with the same conditions besides the number of shots being set to31. The interiors of the through holes 530 and 531 were then filled witha through hole filling resin 532 to be described below and then driedfor 1 hour at 80° C., 1 hour at 120° C., and 30 minutes at 150° C. (seeFIG. 9D). Through holes 530 and 531 were not formed to correspond to all(3000000) power supply pads 162 and ground pads 161 shown in FIG. 8.

The through hole filling resin was prepared as follows. 100 weight partsof bisphenol F epoxy monomer (trade name: E-807; made by Yuka ShellEpoxy Co., Ltd.; molecular weight: 310) were mixed with 6 weight partsof an imidazole curing agent (trade name: 2E4MZ-CN; made by ShikokuCorp.), then 170 weight parts of spherical SiO₂ particles of an averageparticle diameter of 1.6 μm were mixed into this mixture, and bykneading using a three-roll mill, the viscosity at 23±1° C. of themixture was adjusted to 45000 to 49000 cps. The through hole fillingresin was thus obtained.

Through holes 530 a and 531 a were then formed in the through holefilling resin 532 filled in the prior step, roughening was carried outby immersion in a permanganic acid solution, and complete curing wascarried out by drying and curing for 3 hours at 170° C. (see FIG. 9E).Through holes 530 a are through holes that pass through the through holefilling resin 532 and reach the top surface of the wiring pattern 32 ofthe build-up portion 30. The other through holes 531 a are through holesthat pass through the through hole filling resin 532, copper foil 422,and interlayer insulating layer 510 and reach the top surface of thewiring pattern 32 of the build-up portion 30. Through holes 530 a wereformed using a CO₂ laser at conditions of an energy density of 2.0 mjand 2 shots via a mask diameter of 1.4 mmφ, and through holes 531 a wereformed with the same conditions with the exceptions of using a UV laserand the number of shots being set to 52 (output: 3 to 10 w; frequency:30 to 60 kHz).

Thereafter, an electroless copper plating catalyst was added to the topsurface of the substrate and by immersion in the electroless platingsolution described below, an electroless copper plating film 540 of 0.6to 3.0 μm was formed on the top surface of the substrate (see FIG. 10A).The composition of the aqueous electroless plating solution used was:0.03 mol/L of copper sulfate, 0.200 mol/L of EDTA, 0.1 g/L of HCHO, 0.1mol/L of NaOH, 100 mg/L of α,α′-bipyridyl, and 0.1 g/L of polyethyleneglycol (PEG).

A plating resist 541 was then formed by adhering a commerciallyavailable dry film onto the electroless copper plating film 541 andperforming exposure and development (see FIG. 10B), and an electrolyticcopper plating film 542 of 25 μm thickness was formed on portions atwhich the plating resist was not formed (see FIG. 10C). The compositionof the electrolytic copper plating solution used was: 200 g/L ofsulfuric acid, 80 g/L of copper sulfate, and 19.5 ml/L of an additive(Cupracid GL, made by ATOTECH Japan Co., Ltd.). The electrolytic copperplating was carried out under the conditions of a current density of 1A/dm², a duration of 115 minutes, and a temperature of 23±2° C. Platingresist 541 was then peeled off, and the portions on which plating resisthad 541 remained, that is, the portions of electroless copper platingfilm 540, existing between portions of electrolytic copper plating film542, were etched (quick etched) by a sulfuric acid—hydrogen peroxidebased etching solution to form lands 544, connected to the upperelectrode 543 and copper foil 522 (see FIG. 10D).

A stress relaxing sheet 550 (to become the stress relaxing portion 150in FIG. 8) was then adhered onto the upper electrode 543 and lands 544under lamination conditions of a temperature of 50 to 150° C. and apressure of 0.5 to 1.5 MPa, and then drying at 150° C. was carried outfor 1 hour (see FIG. 1E).

The stress relaxing sheet 550 was prepared as follows. That is, a resincomposition, prepared by dissolving 100 weight parts of a naphthalenetype epoxy resin (trade name: NC-7000L; made by NIPPON KAYAKU CO.,LTD.), 20 weight parts of a phenol-xylylene glycol condensate resin(trade name: XLC-LL; made by Mitsui Chemicals Inc.), 90 weight parts ofa carboxylic acid modified NBR with a Tg of −50° C. (trade name: XER-91;made by JSR Co., Ltd.) as crosslinked rubber particles, and 4 weightparts of 1-cyanoethyl-2-ethyl-4-methylimidazole in 300 weight parts ofethyl lactate, was coated using a roll coater (made by CermatronicsBoeki Co., Ltd.) onto a polymethylpentene (TPX) (trade name: OpulanX-88; made by Mitsui Petrochemical Industries Ltd.) film of 42 to 45 μmthickness and thereafter dried for 2 hours at 80° C., 1 hour at 120° C.,and 30 minutes at 150° C. to obtain the stress relaxing sheet of 40 μmthickness. This stress relaxing sheet has a Young's modulus of 500 Mpaat 30° C.

Via holes 560 were then formed at predetermined positions of the stressrelaxing sheet 550 using a CO₂ laser at conditions of an energy densityof 2.0 mj and 1 shot via a mask diameter of 1.4 mmφ (see FIG. 11A).Roughening was then carried out and then the stress relaxing sheet 550was cured completely by drying and curing at 150° C. for three hours. Bythen applying the steps of catalyst addition, chemical copper plating,plating resist formation, electric copper plating, plating resistremoval, and quick etching, via holes 560 were filled with metal andpads (ground pads 161, power supply pads 162, and signal pads 163) wereformed on the upper surfaces of the respective via holes 560 at thetopmost surface, and the multilayer printed wiring board 110 having themounting portion 160 was thereby obtained (FIG. 11B). Ground pads 161connected to the lands 544 and copper foil 542 are connected to theground line, and power supply pads 162 connected to upper electrode 543are connected to the power supply line. Signal pads 163 are connected tothe signal line. Here, the copper foil 522 corresponds to being thefirst layer electrode 141, the copper foil 526 and upper electrode 543correspond to being the second layer electrode 142, the high dielectricconstant layer 524 corresponds to being the high dielectric layer 143,and these make up the layered capacitor portion 140.

At this stage, solder bumps may be formed on the respective terminals ofthe mounting portion 60 (see the description concerning Example 1 forthe forming method). Also, to mount a chip capacitor 173 as shown inFIG. 8, an etching step (so-called tenting) was performed after the stepof FIG. 9B so that one terminal of the chip capacitor 173 will beelectrically connected by a conductor 562 to the first layer electrode141. Though a cupric chloride etching solution was used in the etchingprocess, the process was carried out in a short time so that afteretching the metal layer 526 and high dielectric layer 524, the copperfoil 522 was etched only slightly. Lastly, a metal layer connected tothis copper foil 522 was disposed on the stress relaxing sheet 550 andthe pad 171 was disposed on the upper surface of the metal layers. Thepad 172 to be connected to the other terminal of the chip capacitor 173was formed on the upper surface of a metal filled in one of the viaholes 560 formed in the stress relaxing sheet 550.

The multilayer printed wiring board 110 of Example 2 described aboveprovides the same effects as those of the Example 1. In the presentExample, the opposing area S of the first layer electrode 141 and thesecond layer electrode 142 was determined so that the static capacitanceC of the layered capacitor portion 140 will be 0.5 μF below the die, andbased on this opposing area S, the number and positions of the passageholes 141 a of the first layer electrode 141 and the number andpositions of the passage holes 142 a of the second layer electrode 142were determined. Here, the opposing area S was computed fromC=∈₀·∈_(r)·d/S. That is, since the relative permittivity ∈_(r) of thehigh dielectric constant layer 142 is 1850 and the thickness d thereofis 1.2 μm, by substituting these values in the above equation andsubstituting 0.5 μF as the static capacitance C, the opposing area S wascomputed. ∈₀ is the permittivity of vacuum (constant).

Example 3

FIG. 13 is a longitudinal section (showing only the left side of acentral line) of a multilayer printed wiring board 210 of an Example 3.As shown in FIG. 13, the multilayer printed wiring board 210 of thepresent example has the same core substrate 20 as Example 1, thebuild-up portion 30 in which wiring patterns 22 and 32 laminated via theresin insulating layer 36 at the upper surface of the core substrate 20are electrically connected by means of via holes 34, an interlayerinsulating layer 220, laminated on the build-up portion 30, a layeredcapacitor portion 240, laminated on interlayer insulating layer 220 andarranged with a high dielectric constant layer 243 and the first andsecond layer electrodes 241 and 242 that sandwich the high dielectricconstant layer 243, an interlayer insulating layer 245, laminated on thelayered capacitor portion 240, a stress relaxing portion 250, formed ofan elastic material and laminated on the interlayer insulating 245, amounting portion 260, on which a semiconductor element is mounted, andchip capacitor positioning regions 270, provided at the periphery of themounting portion 260.

In the layered capacitor portion 240 of the present example, the firstlayer electrode 241 is a solid pattern copper electrode that is formedon the lower surface of the high dielectric constant layer 243 and iselectrically connected to the ground pads 261 of the mounting portion260. For the sake of description, ground pads 261 shall be classifiedinto the two types of ground pads 261 x and ground pads 261 y. Of these,ground pads 261 x are electrically connected through via holes 261 a tolands 266 x. These lands 266 x do not have via holes below. Ground pads261 y are connected through via holes 261 a to lands 266 y, and thelands 266 y are electrically connected through via holes 261 b to thefirst layer electrode 241 and to the ground wiring of the wiring pattern32 of the build-up portion 30. The lands 268, which are connected to viaholes 261 b are electrically independent of the second layer electrode242. The lands 266 x connected to the ground pads 261 x and lands 266 yconnected to the ground pads 261 y are electrically connected by awiring 246 (see FIG. 14). All ground pads 261 are thus set to the samepotential. The first layer electrode 241 is thus connected to therespective ground pads 261 and to the ground wiring of the wiringpattern 32 of the build-up portion 30 and is connected via this groundwiring to an external ground line. Also, though the first layerelectrode 241 has passage holes 241 a, through which via holes 262 c tobe described later pass through in a non-contacting manner, since viaholes 262 c are provided in correspondence to a limited number of powersupply pads 262 y as described later, the number of passage holes 241 adoes not have to be large. Consequently, the area of the first layerelectrode 241 can be large and the static capacitance of the layeredcapacitor portion 240 can be high. The number of passage holes 241 a andthe positions at which passage holes 241 a are to be formed aredetermined depending on the static capacitance of the layered capacitorportion 240, etc.

The second layer electrode 242 is a solid pattern copper electrode thatis formed on the upper surface of the high dielectric constant layer 243and is electrically connected to the power supply pads 262 of themounting portion 260. For the sake of description, power supply pads 262shall be classified into the two types of power supply pads 262 x andpower supply pads 262 y. Of these, power supply pads 262 x areelectrically connected through via holes 262 a to lands 267 x and thelands 267 x are electrically connected through via holes 262 b to thesecond layer electrode 242. Power supply pads 262 y are connectedthrough via holes 262 a to lands 267 y, and the lands 267 y areelectrically connected through via holes 262 c to the power supplywiring of the wiring pattern 32 of the build-up portion 30 withoutcontacting first and second layer electrodes 241 and 242. The lands 267x connected to power supply pads 262 x and the lands 267 y connected tothe power supply pads 262 y are electrically connected by a wiring 247(see FIG. 14). All power supply pads 262 are thus set to the samepotential. The second layer electrode 242 is thus connected to therespective power supply pads 262 and to the power supply wiring of thewiring pattern 32 of the build-up portion 30 and is connected via thispower supply wiring to an external power supply line. Power is thussupplied to the second layer electrode 242 from the power supply wiringof the wiring pattern 32 of the build-up portion 30 and through the viaholes 262 c, wiring 274, and via holes 262 b. Also, though the secondlayer electrode 242 has passage holes 242 a, through which via holes 262c pass through in a non-contacting manner, and passage holes 242 b, forsecuring insulation with respect to lands 268, since via holes 262 c areprovided for power supply pads 262 y, which are a portion of powersupply pads 262, and passage holes 242 b are provided in correspondenceto ground pads 261 y, which are a portion of ground pads 261, thenumbers of passage holes 242 a and 242 b do not have to be large.Consequently, the area of the second layer electrode 242 can be largeand the static capacitance of the layered capacitor portion 240 can behigh. The numbers of passage holes 242 a and 242 b and the positions atwhich passage holes 242 a and 242 b are to be formed are determineddepending on the static capacitance of the layered capacitor portion240, etc.

Since the static capacitance of the layered capacitor portion 240 canthus be made high, an adequate decoupling effect can be exhibited andthe transistor of the semiconductor element (IC) mounted on the mountingportion 260 will be unlikely to become short of power. Though groundpads 261 x and ground pads 261 y are connected via the wiring 246 on theinterlayer insulating layer 245 and the power supply pads 262 x andpower supply pads 262 y are connected via the wiring 247 on theinterlayer insulating layer 245, these wirings may be provided on anylayer (including the mounting portion) that is positioned above thesecond layer electrode or on the top surface of the core substrate 20 oron the build-up portion 30. Also, by connecting ground pads 261 x withground pads 261 y and power supply pads 262 x with power supply pads 262y by wirings at any of the layers, via holes 261 a do not have to bedisposed below all ground pads 261 and via holes 262 a do not have to bedisposed below all power supply pads 262. The number of lands in thelayer below the mounting portion can thus be reduced. Since the numberof via holes and the number of lands that need to be provided are thusreduced, a high density can be realized.

The stress relaxing portion 250 is formed of the same elastic materialas in Example 1. Also, ground pads 261, power supply pads 262, andsignal pads 263, disposed on the mounting portion 260, are aligned in alattice-like or zigzag manner in the same manner as Example 1 (see FIG.1), and the numbers of these are the same as those of Example 1. Here,signal pads 263 do not contact any of the first and second layerelectrodes 241 and 242 of the layered capacitor portion 240. Ground pads261 and power supply pads 262 may be aligned in a lattice-like or zigzagmanner near the center and signal pads 263 may be aligned in alattice-like manner, a zigzag manner, or randomly in the periphery. Aplurality of chip capacitor positioning regions 270 are formed in theperiphery of the mounting portion 260. A plurality of pairs of groundpads 271 and power supply pads 272 are formed in the chip capacitorpositioning regions 270, so as to be connected with the ground terminalsand power supply terminals, respectively, of chip capacitors 273.

The respective ground pads 271 are connected via the first layerelectrode 241 of the layered capacitor portion 240 to the negativeelectrode of an external power supply and the respective power supplypads 272 are connected via the second layer electrode 242 to thepositive electrode of the external power supply. In the present example,ground pads 261 and power supply pads 262 respectively correspond tobeing the first pads and the second pads of Claim 9, and via holes 261 band via holes 262 c respectively correspond to being the first rodterminals and the second rod terminals of Claim 9.

The respective ground pads 271 are connected via the first layerelectrode 241 of the layered capacitor portion 240 to the negativeelectrode of an external power supply and the respective power supplypads 272 are connected via the second layer electrode 242 to thepositive electrode of the external power supply. In the present example,ground pads 261 and power supply pads 262 respectively correspond tobeing the first pads and the second pads of Claim 6, and via holes 261a, 261 b, via holes 262 a and 262 b respectively correspond to being thefirst rod terminals and the second rod terminals of Claim 6.

The procedures for manufacturing the multilayer printed wiring board 210of the present example shall now be described with reference to FIGS. 15to 17. FIGS. 13 and 14 are sections taken by cutting a portion below thesemiconductor element, that is, the portion below the die where powersupply pads 261 and ground pads 262 are aligned alternatingly in alattice-like or zigzag manner, and FIGS. 15 and 17 are sections taken bycutting at a portion where power supply pads 261 and ground pads 262 arenot aligned alternatingly.

First, as shown in FIG. 15A, a substrate 600 having the build-up portion30 formed at least on one surface of the core substrate 20 was preparedand using a vacuum laminator, an interlayer insulating layer 610 (athermosetting insulating film; ABF-45SH, made by AJINOMOTO Co., Inc.)was adhered onto the build-up portion 30 under lamination conditions ofa temperature of 50 to 150° C. and a pressure of 0.5 to 1.5 MPa. A highdielectric constant sheet 620 (the preparation procedures of which arethe same as those of the high dielectric constant sheet 520 of Example2), which had been prepared in advance, was then adhered using a vacuumlaminator onto the interlayer insulating layer 610 (to become interlayerinsulating layer 220 of FIG. 13) under lamination conditions of atemperature of 50 to 150° C. and a pressure of 0.5 to 1.5 MPa, anddrying at 150° C. was then carried out for 1 hour (see FIG. 15B). Thecopper foils 622 and 626 of the high dielectric constant sheet 620 wereboth arranged as solid layers without circuits formed therein. The highdielectric constant sheet 620 was then etched by the tenting method.Though a cupric chloride etching solution was used in the etchingprocess, the process was carried out in a short time so that afteretching the copper foil 626 and high dielectric layer 624, copper foil622 was etched only slightly (see FIG. 15C). In FIG. 15C, portions ofthe copper foil 626 were separated by etching to form the isolated lands626 a (to become lands 268 of FIG. 13). Thereafter, an interlayerinsulating layer (to become the interlayer insulating layer 245;thermosetting insulating film; ABF-45SH made by AJINOMOTO Co., Inc.) 628was laminated onto high dielectric constant sheet 620 (FIG. 15D). Thethrough holes 630 were then formed by means of a carbon dioxide gaslaser, UV laser, YAG laser, or excimer laser, etc., at predeterminedpositions of the substrate in the middle of preparation on which theinterlayer insulating layer 628 had been formed (see FIG. 15E). Thethrough holes 630 were formed to pass through the interlayer insulatinglayer 628, high dielectric constant sheet 620, and interlayer insulatinglayer 610 and reach the top surface of the wiring pattern 32 of thebuild-up portion 30. In regard to the laser conditions, a UV laser madeby Hitachi Via Mechanics, Ltd. was used at an output of 3 to 10 W, afrequency of 30 to 60 kHz, and the number of shots was set to 54.

After forming through holes 630, these through holes 630 were filledwith a through hole filling resin 640 (the preparation procedures ofwhich are the same as the through hole filling resin 532 of Example 2)and then dried (see FIG. 16A). Through holes 651, 652, and 653 were thenformed by means of a carbon dioxide gas laser, UV laser, YAG laser, orexcimer laser, etc., at predetermined positions of the substrate in themiddle of preparation (see FIG. 16B). Through holes 651 were formed topass through the through hole filling resin 640 and reach the topsurface of the wiring pattern 32 of the build-up portion 30, throughholes 652 were formed to pass through the interlayer insulating layer628 and reach the top surface of the copper foil 626, and through holes653 were formed to pass through the interlayer insulating layer 628,high dielectric constant sheet 620 (the lands 626 a, high dielectricconstant layer 624, and copper foil 622), and the interlayer insulatinglayer 610 and reach the top surface of the wiring pattern 32 of thebuild-up portion 30. The forming of these through holes 651, 652, and653 was performed in the order of through holes 651 and then throughholes 652 and 653. The depths of the through holes were adjusted bychanging the laser type and the number of laser shots. For example,through holes 651 were formed using a CO₂ laser via a mask diameter of1.4 mmφ at conditions of an energy density of 2.0 mj and 3 shots,through holes 652 were formed under the same conditions with theexception of the number of shots being 1, and through holes 653 wereformed under the same conditions with the exception of using a UV laserand the number of shots being 56 (output: 3 to 10 W; frequency: 30 to 60kHz). Through holes 630 were formed not in correspondence to all powersupply pads 262 shown in FIG. 13 but in correspondence to a portion,that is, power supply pads 262 y, and through holes 653 were formed notin correspondence to all ground pads 261 shown in FIG. 13 but incorrespondence to a portion, that is, ground pads 261 y.

Thereafter, complete curing was carried out by drying and curing at 170°C. for 3 hours. A catalyst was then added to the top surface of thesubstrate, a normal semi-additive method was applied to respectivelyfill through holes 651, 652, and 653 with metal, thereby forming viaholes 262 c, 262 b, and 261 b and forming lands 267 y, 267 x, and 266 yon the upper surfaces of these via holes 262 c, 262 b, and 261 b, andfurthermore, wiring 247, connecting lands 267 x and lands 267 y werealso formed (see FIG. 16C). By this wiring 247, the wiring pattern 32 ofthe build-up portion 30 and copper foil 626 (to become the second layerelectrode 242) become connected. Also, though omitted from illustrationhere, lands 266 x and wirings 246 of FIG. 14 were formed at the sametime. A stress relaxing sheet 670 (to become the stress relaxing portion250; refer to the stress relaxing sheet 550 of Example 2 in regard tothe preparation procedures) was then laminated (see FIG. 16D).

The through holes 680 were then formed at positions of stress relaxingsheet 670 immediately above the respective lands 267 y, 267 x, and 266 y(see FIG. 17A) and by applying roughening, complete curing, catalystaddition, chemical copper plating, plating resist formation, electricalcopper plating, plating resist removal, and quick etching, therespective through holes 680 were filled with metal and pads were formedon the upper surfaces of the filling metal (see FIG. 17B). Via holes 262a and power supply pads 262 y were thereby formed on lands 267 y, viaholes 262 a and power supply pads 262 x were formed on lands 267 x, andvia holes 261 a and ground pads 261 y were formed on lands 266 y. Also,though omitted from illustration here, via holes 261 a and ground pads261 x were formed on lands 266 x of FIGS. 13 and 14. The multilayerprinted wiring board 210 of FIG. 13 was thus obtained. The copper foil622 corresponds to being the first layer electrode 241, the copper foil626 corresponds to being the second layer electrode 242, the highdielectric constant layer 624 corresponds to being the high dielectricconstant layer 243, and these make up the layered capacitor portion 240.In Example 3, if ground pads 261 x are connected at any of the layers(for example, the mounting portion 260) to ground pads 261 y, via holes261 a and lands 266 x are unnecessary. Likewise, if power supply pads262 x are connected at any of the layers (for example, the mountingportion 260) to power supply pads 262 y, via holes 262 a and lands 267x, below power supply pads 262 x, and via holes 262 b are unnecessary.Via holes and lands can thus be reduced.

Solder bumps may thereafter be formed on the respective terminals ofmounting portion 260 (refer to Example 1 concerning the method offorming). If a chip capacitor 273 is to be mounted as shown in FIG. 13,pads 271 and 272 are formed in the same manner as in Example 2.

In the multilayer printed wiring board 110 described in detail above,the same effects as Example 1 described above can be obtained. Inaddition, with the present Example, since charges from an external powersupply source are charged in the high dielectric constant sheet 620 fromthe build-up portion 30 and through via holes 262 c and 262 b, withoutbeing detoured around the layered capacitor portion 240, and the lengthsof wirings connecting the external power supply source to the secondlayer electrode 242, which is the power supply electrode of the layeredcapacitor portion 240, and to the first layer electrode 241, which isthe ground electrode of the layered capacitor portion 240, are thus madeshort, the layered capacitor portion 240 will not likely to be short ofcharges even when a semiconductor element (IC) that is driven at highspeed is mounted onto the mounting portion 260.

With the present Example, the opposing area S of the first layerelectrode 241 and the second layer electrode 242 was determined so thatthe static capacitance C of the layered capacitor portion 240 will be0.5 μF below the die, and based on this opposing area S, the number andpositions of the passage holes 241 a of the first layer electrode 241and the number and positions of the passage holes 242 a and 242 b of thesecond layer electrode 242 were determined. Here, the opposing area Swas computed from C=∈₀·∈_(r)·d/S. That is, since the relativepermittivity ∈_(r) of the high dielectric constant layer 242 is 1850 andthe thickness d thereof is 1.2 μm, by substituting these values in theabove equation and substituting 0.5 μF as the static capacitance C, theopposing area S was computed. ∈₀ is the permittivity of vacuum(constant).

In the above-described manufacturing procedures, the interlayerinsulating layer 628 was laminated after the step of FIG. 15C (see FIG.15D), through holes 630 were formed at predetermined positions ofinterlayer insulating layer 628 (see FIG. 15E), and after fillingthrough holes 630 with through hole filling resin 640 and drying (seeFIG. 16A), through holes 651 were formed in the through hole fillingresin 640 (see FIG. 16B). The following may be carried out instead ofthese steps. That is, after the step of FIG. 15C, a commerciallyavailable dry film is adhered onto the top surface of the substrate,portions of high dielectric constant sheet 620, at positions where viaholes 262 c (see FIG. 16C) are to be formed, are removed by etching atsizes greater than via holes 262 c by the tenting method to formenlarged holes 632 (see FIG. 18A), and the interlayer insulating layer628 is then laminated onto the high dielectric constant sheet 620 sothat the interlayer insulating layer 628 is made to fill enlarged holes632, which had been formed by etching removal priorly, and thereafterdried (FIG. 18B). The steps of Example 3 from the step of formingthrough holes 651, 652, and 653 onward may then be applied. The step offilling through holes 630 can thereby be eliminated.

Example 4

In Example 2, all of through holes 530 and through holes 531 were formedat positions corresponding to the power supply pads and the ground pads.As a result, the static capacitance of the layered capacitor portionbecame 0.4 μF.

Example 5

In Example 3, all of through holes 630 and through holes 653 were formedat positions corresponding to the power supply pads and the ground pads.As a result, the static capacitance of the layered capacitor portionbecame 0.4 μF.

Example 6

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 20 and a high dielectric constant layer of0.6 μm was thereby obtained. Besides this, the same procedures as thoseof Example 2 were carried out. As a result, the static capacitance ofthe layered capacitor portion below the die became 1.0 μF.

Example 7

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 20 and a high dielectric constant layer of0.6 μm was thereby obtained. Besides this, the same procedures as thoseof Example 3 were carried out. As a result, the static capacitance ofthe layered capacitor portion below the die became 1.0 μF.

Example 8

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 1 and a high dielectric constant layer of0.03 μm was thereby obtained. Besides this, the same procedures as thoseof Example 2 were carried out. As a result, the static capacitance ofthe layered capacitor portion below the die became 20 μF.

Example 9

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 1 and a high dielectric constant layer of0.03 μm was thereby obtained. Besides this, the same procedures as thoseof Example 3 were carried out. As a result, the static capacitance ofthe layered capacitor portion below the die became 20 μF.

Example 10

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 4 and a high dielectric constant layer of0.12 μm was thereby obtained. Besides this, the same procedures as thoseof Example 2 were carried out. As a result, the static capacitance ofthe layered capacitor portion below the die became 5 μF.

Example 11

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 4 and a high dielectric constant layer of0.12 μm was thereby obtained. Besides this, the same procedures as thoseof Example 3 were carried out. As a result, the static capacitance ofthe layered capacitor portion below the die became 5 μF.

Example 12

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 2 and a high dielectric constant layer of0.06 μm was thereby obtained. Besides this, the same procedures as thoseof Example 2 were carried out. As a result, the static capacitance belowthe die became 10 μF.

Example 13

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 2 and a high dielectric constant layer of0.06 μm was thereby obtained. Besides this, the same procedures as thoseof Example 3 were carried out. As a result, the static capacitance belowthe die became 10 μF.

Example 14

In Example 8, all of through holes 530 and through holes 531 were formedat positions corresponding to the power supply pads and the ground pads.As a result, the static capacitance became 16 μF.

Example 15

In Example 9, all of through holes 630 and through holes 653 were formedat positions corresponding to the power supply pads and the ground pads.As a result, the static capacitance became 16 μF.

Example 16

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 330 and a high dielectric constant layerof 10 μm was thereby obtained. Besides this, the same procedures asthose of Example 2 were carried out. As a result, the static capacitancebelow the die became 0.06 μF.

Example 17

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 330 and a high dielectric constant layerof 10 μm was thereby obtained. Besides this, the same procedures asthose of Example 3 were carried out. As a result, the static capacitancebelow the die became 0.06 μF.

Example 18

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 10 and a high dielectric constant layer of0.3 μm was thereby obtained. Besides this, the same procedures as thoseof Example 2 were carried out. As a result, the static capacitance belowthe die became 2.0 μF.

Example 19

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 10 and a high dielectric constant layer of0.3 μm was thereby obtained. Besides this, the same procedures as thoseof Example 3 were carried out. As a result, the static capacitance belowthe die became 2.0 μF.

Example 20

In Example 2, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 25 and a high dielectric constant layer of0.75 μm was thereby obtained. Besides this, the same procedures as thoseof Example 2 were carried out. As a result, the static capacitance belowthe die became 0.8 μF.

Example 21

In Example 3, the number of times of repetition of spin coating, drying,and calcining of preparation procedure (4) of the high dielectricconstant sheet was changed to 25 and a high dielectric constant layer of0.75 μm was thereby obtained. Besides this, the same procedures as thoseof Example 3 were carried out. As a result, the static capacitance belowthe die became 0.8 μF.

Example 22

In Example 3, the high dielectric constant sheet was subject to anetching process in advance and portions of the copper foil 626 and highdielectric constant layer 624 were removed. Thereafter, the highdielectric constant sheet was adhered via the interlayer insulatinglayer 610 onto a substrate 600 having the build-up portion 30 formedthereon. That is, the high dielectric constant sheet adhesion step andthe high dielectric constant sheet etching step of Example 3 wereinterchanged. The subsequent steps were the same as those of Example 3.

Example 23

A chip capacitor was mounted onto the multilayer printed wiring board ofExample 4.

Example 23

A chip capacitor was mounted onto the multilayer printed wiring board ofExample 5.

Example 25

In Example 2, the interlayer insulating layer 510 (see FIG. 9A) was usedin place of the stress relaxing portion 150. Besides this, the sameprocedures as those of Example 2 were carried out.

Example 26

In Example 3, the interlayer insulating layer 610 (see FIG. 15A) wasused in place of the stress relaxing portion 250. Besides this, the sameprocedures as those of Example 3 were carried out.

Examples 27 to 49

The multilayer printed wiring boards were manufactured using aninterlayer insulating layer in place of the stress relaxing portion ineach of Examples 2 to 24, and were respectively indicated as Examples 27to 49.

Comparative Example

A high dielectric constant sheet of a comparative example was preparedbased on the preparation procedures of the other form of the highdielectric constant sheet described in Example 2. However, calcining wasnot performed and electrodes were formed on an uncalcined layer afterdrying. Besides this, the same procedures as those of Example 2 werecarried out. As a result, the static capacitance below the die becameless than 0.001 μF.

[Evaluation Test 1]

An IC chip with a drive frequency of 3.6 GHZ and an FSB of 1066 MHz wasmounted onto the multilayer printed circuit board of each of Examples 2to 49, simultaneous switching was repeated 100 times, and whether or noterroneous operation occurred was checked using a pulse patterngenerator/error detector (trade name: D3186/3286; made by ADVANTESTCORPORATION).

[Evaluation Test 2: HAST]

The multilayer printed circuit board of each of Examples 2 to 49 wasplaced in an environmental tester set to 85° C.×85% for a total of 50hours while applying a voltage of 3.3V across the first layer electrodeand the second layer electrode. Discharge was carried out every 2 hoursduring this time. Thereafter, an IC chip with a drive frequency of 3.6GHZ and an FSB of 1066 MHz was mounted, simultaneous switching wasrepeated 100 times, and whether or not erroneous operation occurred waschecked using the above-described pulse pattern generator/errordetector.

[Evaluation Test 3: HAST]

Each multilayer printed circuit board, which had been subject toEvaluation Test 2, was placed in an environmental tester set to 85°C.×85% for a total of 50 hours while applying a voltage of 3.3V acrossthe first layer electrode and the second layer electrode as inEvaluation Test 2. Discharge was carried out every 2 hours during thistime. Thereafter, an IC chip with a drive frequency of 3.6 GHZ and anFSB of 1066 MHz was mounted, simultaneous switching was repeated 100times, and whether or not erroneous operation occurred was checked usingthe above-described pulse pattern generator/error detector.

[Evaluation Test 4: Heat Cycle]

The following heat cycle test was carried out on the multilayer printedcircuit board of each of Examples 2 to 26. Heat cycle test conditions: Acycle of −55° C.×30 minutes and 125° C.×30 minutes was repeated 100times or 500 times. Thereafter, an IC chip with a drive frequency of 3.6GHZ and an FSB of 1066 MHz was mounted, simultaneous switching wasrepeated 100 times, and whether or not erroneous operation occurred waschecked using the above-described pulse pattern generator/errordetector.

[Evaluation Test 5]

In place of the IC chip with a drive frequency of 3.6 GHZ and an FSB of1066 MHz of Evaluation Test 1, an IC chip with a drive frequency of 5.7GHZ and an FSB of 1066 MHz was mounted and the same test as EvaluationTest 1 was conducted. As a result, erroneous operation did not occurwith multilayer printed wiring boards, with which the static capacitancebelow the die is not less than 1.0 μF.

[Evaluation Results]

The results of Evaluation Tests 1 to 4 are shown in Table 1. In table 1,a ∘ indicates that erroneous operation was not observed and a xindicates that erroneous operation was observed. The static capacitancebelow the die and the evaluation results of Evaluation Tests 1 to 3 forExamples 27 to 49 were the same as those of Examples 2 to 24,respectively, though not shown in Table 1.

TABLE 1 Evaluation test results μ μ 1 2 3 4*² 4*³ Example 2 Partial 1.20.5 Not ∘ ∘ x ∘ x mounted Example 3 Partial 1.2 0.5 Not ∘ ∘ x ∘ xmounted Example 4 All 1.2 0.4 Not ∘ x x ∘ x mounted Example 5 All 1.20.4 Not ∘ x x ∘ x mounted Example 6 Partial 0.6 1.0 Not ∘ ∘ ∘ ∘ ∘mounted Example 7 Partial 0.6 1.0 Not ∘ ∘ ∘ ∘ ∘ mounted Example 8Partial 0.03 20 Not ∘ — — ∘ x mounted Example 9 Partial 0.03 20 Not ∘ —— ∘ x mounted Example 10 Partial 0.12 5 Not ∘ ∘ ∘ ∘ ∘ mounted Example 11Partial 0.12 5 Not ∘ ∘ ∘ ∘ ∘ mounted Example 12 Partial 0.06 10 Not ∘ ∘x ∘ x mounted Example 13 Partial 0.06 10 Not ∘ ∘ x ∘ x mounted Example14 All 0.03 16 Not ∘ x x ∘ x mounted Example 15 All 0.03 16 Not ∘ x x ∘x mounted Example 16 Partial 10 0.06 Not ∘ x x ∘ x mounted Example 17Partial 10 0.06 Not ∘ x x ∘ x mounted Example 18 Partial 0.3 2.0 Not ∘ ∘∘ ∘ ∘ mounted Example 19 Partial 0.3 2.0 Not ∘ ∘ ∘ ∘ ∘ mounted Example20 Partial 0.75 0.8 Not ∘ ∘ ∘ ∘ ∘ mounted Example 21 Partial 0.75 0.8Not ∘ ∘ ∘ ∘ ∘ mounted Example 22 Partial 1.2 0.3 Not ∘ — — ∘ x mountedExample 23 All 1.2 0.4 Mounted ∘ ∘ ∘ ∘ ∘ Example 24 All 1.2 0.4 Mounted∘ ∘ ∘ ∘ ∘ Example 25 Partial 1.2 0.5 Not ∘ — — ∘ x mounted Example 26Partial 1.2 0.5 Not ∘ — — ∘ x mounted Comparative Partial 5 <0.01 Not x— — x — Example 1 mounted *¹C/C = chip capacitor *²after 100 cycles*³after 500 cycles

The results of Evaluation Test 1 show that by using a high dielectricconstant material, which has been calcined apart from the build-upportion and thereby made into a ceramic, as the high dielectric constantlayer, the dielectric constant can be adequately high and instantaneousdrops of electrical potential can thereby be restrained.

Also, the results of Evaluation Test 4 show that the Comparative Examplecannot accommodate for instantaneous potential drops of the IC chipafter 100 cycles. Though the cause is not clear, it is presumed that dueto the weak joining of high dielectric constant particles, cracksdevelop and lead to loss of capacitor functions.

Also Example 22, in which a circuit is formed on the high dielectricconstant sheet prior to adhesion onto the build-up portion, cannotaccommodate for instantaneous potential drops of the IC chip after beingsubject to the heat cycle test. Though the cause is not clear, it ispresumed that due to the heat cycle test, cracks developed from portionsat which the pressure concentrates in the lamination process.

Examples 25 and 26 that do not have stress relaxing portions also cannotaccommodate for instantaneous potential drops of the IC chip after beingsubject to the heat cycle test. Though the cause is not clear, it ispresumed that since the stress relaxing portion is not provided, cracksor starting points of cracks were formed in the high dielectric constantlayer due to stress resulting from the thermal expansion coefficientdifference between the IC chip and the multilayer printed wiring board.It is considered that when starting points of cracks are formed in theheat cycle test, the repeated charging and discharging of the highdielectric constant layer in the simultaneous switching test lead to theforming of cracks due to the displacement of particles in this process.

Furthermore, Examples 4 and 5, in which the static capacitance below thedie is not more than 0.4 μF, cannot accommodate for instantaneouspotential drops of the IC chip after being subject to Evaluation Test 2.Though the cause is not clear, it is presumed that due to the HAST test,the high dielectric constant layer became degraded, lowered in relativepermittivity, and thereby unable to exhibit an adequate decouplingeffect. Also, whereas when the static capacitance below the die becomesnot more than 0.5 μF, instantaneous potential drops of the IC chipcannot be accommodated after Evaluation Test 2, problems did not occurwith Examples 23 and 24 having the same static capacitances below thedie as Examples 4 and 5. Though the cause is not clear, it is presumedthat instantaneous potential drops of the IC chip are accommodated bythe additional supply of power from the chip capacitor. Furthermore,even with Examples 14 and 15, which are high in static capacitance,instantaneous potential drops of the IC chip cannot be accommodatedafter Evaluation Test 2. Though the cause is not clear, it is presumedthat due to the high static capacitance, the influence of the HAST testis received more readily and the high dielectric layers thus underwentdielectric degradation or dielectric breakdown.

In Examples 12 to 15 with high static capacitance, the results ofEvaluation Test 4*³ are x. It is presumed that since with a dielectricmaterial, crystal displacement occurs when charging and discharging arerepeated and stress accumulated in the heat cycle is added to thisstress due to displacement, the relative permittivity of the highdielectric constant layer degrades, thus leading to x results. Theresults of Evaluation Test 4*³ are also x for Examples 2 to 5, 16, and17, which are comparatively low in static capacitance. This is presumedto be due to the relative permittivity of the high dielectric constantbecoming degraded by expansion and contraction of the dielectricmaterial in the heat cycle test and causing the static capacitance belowthe die to decrease, thus leading to x results.

The results of Table 1 show that when the static capacitance below thedie is 0.8 to 5 μF, instantaneous voltage drops of the transistor of theIC can be accommodated even after an environment test and since problemsdo not occur even after conducting an HAST test or a heat cycle test,the insulation reliability and the connection reliability are extremelyhigh.

Though in all of the Examples, the first layer electrode was used forground and the second layer electrode was used for power supply, thisrelationship may be reversed.

The multilayer printed wiring board of the present invention is used formounting an IC chip or other semiconductor element and can be used, forexample, for electric-related industries and communication-relatedindustries.

What is claimed is:
 1. A printed wiring board comprising: a main bodyhaving a surface, the surface of the main body having a mounting portionin which a plurality of ground pads and a plurality of power supply padsof are formed and positioned to mount a semiconductor element; and alayered capacitor portion disposed in the main body and comprising ahigh dielectric constant layer and first and second layer electrodessandwiching the high dielectric constant layer, wherein the highdielectric constant layer of the layered capacitor portion comprises aceramic high dielectric constant sheet prepared by calcining in advancea high dielectric constant material, one of the first and second layerelectrodes is electrically connected to the plurality of power supplypads, the other one of the first and second layer electrodes iselectrically connected to the plurality of ground pads, the first layerelectrode is connected to one of the plurality of ground pads and theplurality of power supply pads through a plurality of rod terminals,passing through the second layer electrode in a non-contacting manner,and the plurality of rod terminals is provided in a fewer number than anumber of the one of the plurality of ground pads and the plurality ofpower supply pads.
 2. The printed wiring board according to claim 1,wherein the high dielectric constant layer is prepared by calcining araw material comprising at least one metal oxide selected from the groupconsisting of: barium titanate, strontium titanate, tantalum oxide, leadzirconate titanate, lead lanthanum zirconate titanate, lead niobiumzirconate titanate, lead calcium zirconate titanate, and lead strontiumzirconate titanate.
 3. The printed wiring board according to claim 1,wherein at least one of the rod terminals passes through the first andsecond layer electrodes in a non-contacting manner.
 4. The printedwiring board according to claim 1, wherein the first layer electrode isformed as a solid pattern having passage holes through which a pluralityof rod terminals connected to the second layer electrode passes in anon-contacting manner, and the second layer electrode is formed as thesolid pattern having passage holes through which a plurality of rodterminals connected to the first layer electrode passes in anon-contacting manner.
 5. The printed wiring board according to claim 1,wherein the layer electrode is connected to the plurality of rodterminals passing through the second layer electrode in a non-contactingmanner, the plurality of power supply pads includes pads which areelectrically connected via the rod terminals to the first layerelectrode and an external power supply line, the plurality of powersupply pads includes pads which are not connected via the rod terminalsand are electrically connected to the pads connected with the rodterminals, the second layer electrode is connected to a plurality ofsecond rod terminals passing through the first layer electrode in anon-contacting manner, the plurality of ground pads includes pads whichare electrically connected via the second rod terminals to the secondlayer electrode and an external ground line, and the plurality of groundpads includes pads which are not connected via the second rod terminalsand are electrically connected to the pads connected with the second rodterminals.
 6. The printed wiring board according to claim 5, wherein therod terminals and the second rod terminals are aligned at leastpartially alternatingly in a lattice or zigzag formation.
 7. The printedwiring board according to claim 1, wherein in the layered capacitorportion, the distance between the first and second layer electrodes isset to a distance which is not more than 10 μm and which shortcircuiting does not occur.
 8. The printed wiring board according toclaim 1, wherein the layered capacitor portion is formed directly belowthe semiconductor element that is mounted onto the mounting portion. 9.The printed wiring board according to claim 1, further comprising: achip capacitor installed on the surface of the main body, wherein thechip capacitor is connected to the first and second layer electrodes.10. The printed wiring board according to claim 1, wherein the main bodyhas a stress relaxing portion comprising an elastic material anddisposed between the mounting portion and the layered capacitor portion.11. The printed wiring board according to claim 10, wherein the stressrelaxing portion is formed only directly below the semiconductor elementthat is mounted onto the mounting portion.
 12. The printed wiring boardaccording to claim 1, wherein the second layer electrode is connected tothe other one of the plurality of ground pads and the plurality of powersupply pads through a plurality of rod terminals passing through thefirst layer electrode in a non-contacting manner, and the plurality ofrod terminals is aligned in a lattice formation.
 13. The printed wiringboard according to claim 1, wherein the second layer electrode isconnected to the other one of the plurality of ground pads and theplurality of power supply pads through a plurality of rod terminalspassing through the first layer electrode in a non-contacting manner,and the plurality of rod terminals is aligned in a zigzag formation. 14.The printed wiring board according to claim 1, wherein the plurality ofrod terminals passing through the second layer electrode is aligned in alattice formation.
 15. The printed wiring board according to claim 1,wherein the plurality of rod terminals passing through the second layerelectrode is aligned in a zigzag formation.